Research On Critical Problem Of Three-phase Traffic Flow Under The Disturbance Moving Bottleneck

With the further construction and improvement of China's expressway infrastructure,the number of lanes has gradually increased to multi-lane,and the disturbance caused by the fixed bottleneck of traffic lanes has had a smaller impact on traffic flow,but the impact of random disturbances within the traffic stream is increasing.This kind of disturbance is not easy to be discovered by people and is difficult to predict.One of the main reasons for this is that there are many heavy-duty trucks with poor performance in the mixed traffic flow of expressways.These vehicles and rapid vehicles generate a lot of "mobile bottleneck" effects.The“mobile bottlenecks”effect is generally caused by the disturbance behavior of large-scale vehicles.Unlike the fixed bottleneck of highways,the loss of space-time resources caused by moving bottlenecks dynamically changes with time and space,and to a certain extent causes the internal velocity of traffic flow.Random disturbances,diffusion leads to the formation of crowded traffic.The analysis of the form and mechanism of the movement of bottleneck disturbances to reveal their influence on the traffic flow is of great significance for the formulation of reasonable measures to eliminate the phenomenon of “mobile bottlenecks”on highways in China.In the framework of the three-phase traffic flow theory,this paper simulates and analyzes the bottleneck of the highway moving,discusses the form of the bottleneck disturbance and numerically simulates it,and reveals its influence on traffic flow capacity.The research points are summarized as follows:(1)First introduce the research background and research status of “mobile bottlenecks”at home and abroad,and then elaborate the relevant content of the three-phase traffic flow theory.Take the critical phase transition characteristics of traffic flow as the research entry under the“mobile bottleneck”disturbance Pointed,combined with three-phase traffic flow theory proposed research methods and technical routes.(2)On the basis of introducing the classic three-phase traffic flow model related to this research,taking the MVDE model as an example,the deficiencies in the model rules are analyzed from the perspective of actual traffic characteristics.Combined with the driver's sensitivity characteristics,the dynamic synchronization distance is considered.The factors of the acceleration of the next vehicle will subdivide the constant acceleration value during the acceleration step,modify the updating rules in the model,and establish a new cellular automata model and perform fitting verification.The steady-state solution of the model is calculated.The results are similar to the basic assumptions of the three-phase traffic flow theory.The quantitative analysis combines the spatio-temporal evolution map with the statistically derived flow-density and velocity-density maps.Local micrographs of the flow state and correlation angles quantitatively verify the microscopic features of the regions where the synchronization flows exist.The results show that the model can simulate three kinds of traffic flow phases and first-order phase transition phenomena,and there is no long-range correlation in the autocorrelation and cross-correlation under synchronous flow,indicating that the improved model is a three-phase traffic flow theory cell.Automatic machine model.(3)In the improved single-lane three-phase traffic flow model,the mobile bottleneck,the basic parameters of the car are adjusted,and the disturbance caused by the inherent attributes of the mobile bottleneck is measured from three indicators of the mobile bottleneck different import probability,different maximum vehicle speeds and different vehicle lengths.Effect,study its disturbance characteristics of traffic flow.The results show that the maximum flow rate decreases with the increase of the proportion of mobile bottlenecks.When the proportion of mobile bottlenecks in the hybrid traffic flow is greater than half,the continuous increase in the ratio has little effect on the flow in the low and medium density areas,and the average speed of the lane changes with the movement.The proportion of bottlenecks increases and decreases.The decline in the low-medium density areas is more obvious.When the proportion of mobile bottlenecks is more than half,the proportion of the bottleneck continues to increase and has little effect on the average speed of the lane;the smaller the maximum speed of movement bottlenecks,the corresponding The smaller the maximum flow rate,the less effective the effect is in the low-medium density area.The average speed of the lane decreases with the decrease of the maximum speed of the bottleneck.The maximum flow rate and the average speed of the lane decrease with the length of the moving bottleneck.However,the longer the bottleneck that moves in the high-density area,the more obvious the disturbance effect.(4)Based on the intrinsic property perturbation model of the mobile bottleneck,a two-lane three-phase mixed traffic flow model is proposed and verified by the basic map.The verification results also conform to the basic assumptions of the three-phase traffic flow theory.Based on the characteristics of major disturbance behaviors of mobile bottlenecks,a cellular automata model was established to analyze the main disturbance behaviors of mobile bottleneck lane change and combination,and its impact on traffic flow was analyzed.In the mobile bottleneck lane change perturbation model,the lane change rules of large and small cars are set up respectively to carry out numerical simulation.The results show that under the synchronized flow state,the lane change of the mobile bottleneck has the dual effect of causing congestion and dissipating the congestion,and the traffic density becomes higher.Larger,the more disturbing effect the mobile bottleneck changes.At the same time,with the increase of the density,the degree of local congestion caused by the change of the mobile bottleneck is also getting faster and faster.In the combined model of mobile bottleneckperturbation,the condition and form of the combination behavior of mobile bottleneck are discussed.The corresponding rules are added to the model for numerical simulation.The results show that the serial perturbation effect of the mobile bottleneck has an impact on the free flow and the synchronous flow.The serial number of bottlenecks increased,the higher the occupancy rate of the slow lane,the flow and the average speed of the entire lane were in a downward trend.The parallel disturbance effect of the mobile bottlenecks has the most significant effect on the free flow,and the range of impact depends on the size of the parallel bottleneck of the mobile bottleneck.It has been found that the variation of the flow and speed of the parallel car spacing with the bottleneck of the bottleneck between 30 m and 90 m is the most obvious.The parallel disturbance effect has little effect on the synchronization flow and is not the main factor that causes the phase transition under the synchronous flow.